Types of Dementia
Alzheimer’s disease is the most common cause of dementia. Around 62% of people with dementia will have Alzheimer’s disease, which is named after the doctor who first described it (Alois Alzheimer). It is a physical disease that affects the brain.
During the course of the disease, proteins build up in the brain to form structures called ‘plaques’ and ‘tangles’. This leads to the loss of connections between nerve cells, and eventually to the death of nerve cells and loss of brain tissue.
People with Alzheimer’s also have a shortage of some important chemicals in their brain. These chemical messengers help to transmit signals around the brain. When there is a shortage of them, the signals are not transmitted as effectively.
Current treatments for Alzheimer’s disease can help boost the levels of chemical messengers in the brain, which can help with some of the symptoms. Alzheimer’s is a progressive disease. This means that gradually, over time, more parts of the brain are damaged. As this happens, more symptoms develop. They also become more severe.
Vascular dementia is caused by reduced blood supply to the brain due to diseased blood vessels. Around17% of people with dementia will have vascular dementia.
To be healthy and function properly, brain cells need a constant supply of blood to bring oxygen and nutrients. Blood is delivered to the brain through a network of vessels called the vascular system. If the vascular system within the brain becomes damaged - so that the blood vessels leak or become blocked - then blood cannot reach the brain cells and they will eventually die.
This death of brain cells can cause problems with memory, thinking or reasoning. Together these three elements are known as cognition. When these cognitive problems are bad enough to have a significant impact on daily life, this is known as vascular dementia.
Dementia with Lewy Bodies
Dementia with Lewy bodies (DLB) accounts for around 4 per cent of all recorded dementia, but there is good evidence that the condition is not always diagnosed correctly. Based on studies of brain tissue after death, scientists think DLB may account for as much as 10-15 per cent of all dementia.
DLB appears to affect men and women equally. As with Alzheimer's disease and vascular dementia, DLB becomes more common over the age of 65. However, it can also affect people under 65.
Other than age, there are few risk factors (such as medical conditions or lifestyle choices) that are known to increase a person's chances of developing DLB. Most people who develop DLB have no clear family history of the condition. A few families seem to have genetic mutations that are linked to inherited Lewy body disease, but these are very rare.
Frontotemporal dementia (FTD) covers a wide range of different conditions. It is sometimes called Pick’s disease or frontal lobe dementia. This page explains what FTD is, its symptoms, and who gets it. It also describes how it is diagnosed and the treatment and support that is available. Around 2% of people with dementia will have frontal lobal dementia
The word ‘frontotemporal’ refers to the lobes of the brain that are damaged in this type of dementia. The frontal lobes of the brain, found behind the forehead, deal with behaviour, problem-solving, planning and the control of emotions. An area of usually the left frontal lobe also controls speech.
The temporal lobes – on either side of the brain – have several roles. The left temporal lobe usually deals with the meaning of words and the names of objects. The right temporal lobe is usually involved in recognising faces and familiar objects.
Other types of dementia
Other types of dementia
There are several other causes of dementia which are less common than Alzheimer’s or Vascular dementia. Some of those types of dementia could be conditions such as
Creutzveld Jacob disease
New variant CJD
Inoperable brain tumours
It is also possible to have a combination of different types of dementia. It isn’t unusual to have both Alzheimer’s disease along with Vascular dementia.